1. Field of Invention
This invention relates to mechanical tremolo devices for stringed instruments such as guitars, and more specifically to a tremolo handle mounting mechanism.
2. Description of Prior Art
There have been numerous tremolo or vibrato devices described in prior patents. Many of the features embodied in the device discussed herein were achieved in one or more such prior patents. The patent which embodies features most nearly connected to the present invention in general shape and principles of operation is U.S. Pat. No. 3,056,329 to Paul D. Butts (1962). The string engaging saddle, spring, and tailpiece as described in that prior patent are shaped very nearly the same and operate under the same principle as described below, except that the handle mounting mechanism differs from the marketed version. The modified handle mounting mechanism was not patented, but was included in the marketed versions of the device. A description of this mechanism is given hereinafter, in order that the present invention may be clearly understood. The basic features of the above cited tremolo device are as follows:
(1) a tailpiece which fastens to a musical instrument on one end and a spring on the other end;
(2) a spring in the shape of a curved plate with ends bent to form attachment clips;
(3) a string engaging saddle which engages both the spring and the strings of a musical instrument, and;
(4) a handle with mechanism attaching it to the string engaging saddle.
The above parts are held together and fastened to a musical instrument by various means. The assembled parts form a mechanical tremolo device. The string engaging saddle floats in a centered position under the opposing forces of the instrument's strings on one hand, and the spring on the other hand. The device produces a tremolo effect when a musician playing the instrument moves the string engaging saddle back and forth across it's centered position by means of the attached handle. The above movement alternately loosens and tightens the tension of the strings, thereby lowering or raising the pitch of the sound produced by the strings. The handle may be rotated laterally to move it out of the way of the player's hand, when he or she does not wish to use the tremolo. To facilitate this lateral rotation, the handle is attached to one side of a cylindrical shape on it's mounting end, with flat surfaces on the top and bottom of the cylinder, parallel with each other and perpendicular to the cylinder's sides. The cylinder slips over a permanently attached round post projecting outwardly from the string engaging saddle to a length approximately equalling the depth of the cylinder's sides. The post is flat on top and is provided with a threaded hole extending down through it's center and a flat surface around it's base to mate with the bottom of the handle's cylindrical end. The assembly of these rotatably interconnected parts is retained from relative separation by a headed screw with a flat ring washer of suitable resilient material interposed between the screw head and the top of the post and cylinder. The screw is intended to hold the handle in any desired position when appropriately tightened. The handle mounting mechanism described above is not covered by any patent of which the applicant is aware, but has been in use for many years; therefore, is described herein only so that the improvements embodied in the present invention can be clearly illustrated.
There are two deficiencies of the string mounting mechanism described above wherein improvements are believed by the applicant to be desirable, new, and useful: (1) the screw that secures the handle tends to loosen unexpectedly while the instrument is being played, allowing the handle to drop out of it's lateral position, and; (2) no provision has been made, short of removing and permanently bending the handle, for adjusting it's height at the unsupported end where the player grasps it Since the player pushes this unsupported end of the handle down toward the top surface of the instrument to lower the string tension, or pulls it up away from the top surface to raise the string tension, the handle's unsupported end needs to be at an appropriate level in order to be used effectively and comfortably.
In analyzing deficiency (1) described on page 2 above, it was found that excessive frictional drag will occur between the handle cylinder's top and the washer and screw. The design of the prior art device did not take into account the fact that equal force would be applied to unequal bearing surfaces. The top of the cylinder, having a larger diameter than the post, has a greater bearing surface area than the top of the post, which results in more total frictional drag on the cylinder's bearing surface than is imposed on the bearing surface on the top of the post. Since the post cannot rotate, the washer is carried in rotation with the cylinder by the greater friction, often rotating the screw with the washer. Adding to the problem, the bearing surfaces tend to develop unevenness; in effect, they tend to become tight in one rotational position, and loose in another, causing the flat washer to bind up on the bottom of the screw head and the top of the cylinder when the handle is rotated clockwise. Then when the handle is rotated counter-clockwise, the screw and washer turn with the cylinder, loosening the assembly and allowing the handle to fall out of it's position when released by the player.
The deficiency of (2) described on page 2 above, was not addressed in the cited U.S. Pat. No. 3,056,329 or in it's unpatented modifications. Other patents may have provided a means to adjust the handle height in various designs and types of tremolos, but to my knowledge, no means of adjustment has been provided for the particular style of tremolo discussed herein, specifically the type of handle mounting mechanism considered above. A user of this type of tremolo has heretofore been required to remove the handle, bend it in a vise or something similar, and reinstall it in order to change the height. This height of the unsupported end of the handle is dependent upon the angle at which the string engaging saddle comes to rest when the spring tension versus the collective tension of all the instrument's strings is equalized. Many different gauges of strings are available; light, medium, and heavy, with various combinations offered in sets or individually by several competing manufacturers. Heavy gauge strings apply more tension on the spring than light gauge strings do, pulling the handle down toward the top of the instrument. Conversely, light gauge strings apply less tension on the spring than do heavy gauge strings, so that the unsupported end of the handle rests relatively higher. One can see that the height of the tremolo handle can not be accurately predicted, either when the device is first installed and strings attached and tuned, or when a set of strings is put on the instrument which are lighter or heavier than the user has adjusted the handle height for. For this reason, an easy adjustment is needed.